WO2015039754A1

WO2015039754A1 - Sensor for emitting an electrical signal based on a path to be detected

Info

Publication number: WO2015039754A1
Application number: PCT/EP2014/002532
Authority: WO
Inventors: Stephan BRÜGGEMANN
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 2013-09-18
Filing date: 2014-09-18
Publication date: 2015-03-26
Also published as: EP3047239A1; DE102013218734A1; CN105556252A

Abstract

The invention relates to a sensor (16) for emitting an output signal which is dependent on a rotation angle (18), comprising a shaft (34), which is rotatable around the rotation angle (18), a field encoder element (30) fastened to an axial end (39) of the shaft (34) for outputting a physical measurement field (32) and an evaluation circuit (28) arranged spaced apart from the field encoder element (30), having an air gap (31), for generating the output signal based on the physical measurement field (32), wherein the field encoder element (30) is designed such that the air gap (31) is variable in dependence on the rotation angle (18).

Description

A sensor for outputting an electrical signal based on a path to be detected

The invention relates to a sensor for outputting an electrical signal based on a path to be detected, in particular an angle and a method for producing a sensor, in particular of the angle sensor.

WO 2006/029 946 A1 discloses a sensor with a field transmitter element in the form of a transmitter magnet and an evaluation circuit for detecting a magnetic field emitted by the transmitter magnet. The transmitter magnet can be moved over a path to be detected, such as a rotation angle, wherein the evaluation circuit detects the rotation angle based on the magnetic field emitted by the encoder magnet and outputs in an output signal. The sensor is therefore also called an angle sensor.

It is an object of the invention to improve the known sensor.

The object is solved by the features of the independent claims. Preferred developments are the subject of the dependent claims. In accordance with one aspect of the invention, a sensor for outputting an output signal dependent on a rotation angle comprises a shaft rotatable about the rotation angle, a rim encoder element rotationally fixed to one axial end of the shaft for outputting a physical measurement field and an evaluation circuit arranged at an air gap at a distance from the field sensor element for generating the output signal based on the physical measuring field, wherein the rim encoder element is designed such that the air gap is variable in dependence on the rotation angle. The specified sensor is based on the consideration that the field-sensor element could be formed in a circle around an axis of rotation of the shaft. In this way, in each rotation angle of the shaft, a part of the field-generating element and thus of the

CONFIRMATION COPY physical measuring field are directed to the evaluation circuit, so that the rotation angle of the shaft would be detectable in principle over a complete rotation of the shaft. On the other hand, the physical measuring field of a single range is sufficient

Feldpols, which is emitted by the field element, not so that the evaluation circuit can detect the rotation angle of the shaft based on the physical field of view, because the physical field of view would have to change depending on the angle of rotation.

For this purpose, although a dipole, such as a magnet could be used as a field sensor element, in which the physical measuring field is composed of a superposition of two sub-fields, which are delivered from one field pole. At certain angles of rotation, however, a field pole with its subfield dominates the physical measuring field so strongly that the other subfield no longer has any influence on the physical measuring field. The physical measuring field can therefore continue to change in these rotation angle ranges depending on the angle of rotation, so that no clear detection of the rotation angle is possible.

In order to still enable the unambiguous detection, a variable air gap between the field generator element and the evaluation circuit is used as a function of the angle of rotation within the scope of the specified sensor. In this way, not only the physical measuring field itself, but also its effect, which it has on the evaluation circuit varies depending on the angle of rotation. As a result, the evaluation circuit can generate an output signal which is dependent on the angle of rotation independently of whether or not the physical measuring field changes as a function of the angle of rotation.

The variable air gap is defined as a function of the angle of rotation as the shortest distance between the field sensor element and the evaluation circuit.

In a development of the specified sensor includes the Field sensor element in the circumferential direction to the angle of rotation considered two, for example, the aforementioned field poles, wherein the variable air gap is the lowest, when one of the two field poles lies on a line through a rotation axis of the shaft and the evaluation circuit. In this way, the largest signal jumps can be achieved in the evaluation signal depending on the rotation angle, so that the rotation angle can be detected with a maximum sensitivity.

The variable air gap can be arbitrarily formed, for example, by an axially helical field transmitter element. In a particular embodiment of the specified sensor, the variable air gap is formed by the use of at least one radially and / or axially protruding from the field sensor element projection. Expediently, the variable air gap should be realized by geometrical measures on the field-emitting element and / or on the evaluation circuit, which is technically feasible in terms of cost and time.

In another refinement of the specified sensor, the variable air gap is formed by at least two projections projecting radially and / or axially from the field generator element, which are arranged point-symmetrically with respect to each other. In this way, a symmetrical output signal can be output via the rotation angle, which is particularly easy to evaluate in terms of computation.

In a still further development of the specified sensor, the projection in the direction of the angle of rotation is substantially equal to a detection range of the evaluation circuit in the direction of the angle of rotation. In this way, the occurrence of a constant output signal over a range of values of the rotation angle can be avoided even better. In an alternative development of the specified sensor, the field-transmitting element is elliptical in the axial and / or radial direction as viewed from the shaft for the evaluation circuit. The elliptical field generator element forms an output signal as a function of the angle of rotation, which approximates a sinusoidal shape and is largely free of harmonics. From such a sinusoidal signal, the rotation angle can be derived in a technically particularly simple manner.

The physical measuring field can be designed as desired. Particularly preferably, the physical measuring field is a magnetic field. In a preferred embodiment of the specified sensor, the field-emitting element is therefore a magnet which can be used as a permanent magnet without electrical power supply in the sensor.

In a particularly preferred development of the specified sensor, the field-emitting element is arranged axially spaced from the shaft and radially spaced from a rotational axis of the shaft, which can be represented on a particularly small space.

According to a further aspect of the invention, a method for producing a sensor configured for outputting an output signal dependent on a rotational angle, in particular one of the above sensors, comprises the steps of providing a shaft rotatable about the rotational angle injection molding of a device arranged to output a physical measuring field

Field encoder element to an axial end of the shaft, and arranging an evaluation circuit viewed from the shaft axially in front of the field generator element, which is adapted based on the physical measuring field to produce the output signal.

In a further development, the specified method comprises the step of forming an anti-twist device at the axial end prior to injection of the field-transmitting element.

In yet another development of the stated method, a material of the field sensor element sprayed onto the shaft comprises a filler in which magnetic particles are accommodated.

In accordance with another aspect of the invention, the sensor is for output an output dependent on a rotation angle output signal one of the specified methods.

The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings, in which:

1 is a schematic view of a vehicle with a chassis control system,

FIG. 2 shows a sensor for detecting an acceleration between a wheel and a chassis in the vehicle of FIG. 1, FIG.

FIG. 3 is a perspective view of part of the sensor of FIG. 2; FIG. Fig. 4 in a partial sectional view of a part of a shaft into which a field sensor element for the sensor of FIG. 2 is injectable, and

Fig. 5 in a partial sectional view of the part of the shaft of Fig. 4, to which the field-emitting element is molded for the sensor of Fig. 2, show.

In the figures, the same technical elements are provided with the same reference numerals and described only once.

Reference is made to Fig. 1, which shows a schematic view of a vehicle 2 with a chassis control system 4.

In the context of this suspension control system 4 lifting, pitching and rolling movements of a chassis 6 with respect to a non-illustrated road on the stationary wheels 8 of the vehicle 2 in a vertical axis 10 stationary rolls are minimized to the driving characteristics of the vehicle 2 when driving in a To improve direction of travel 12.

For this purpose, the suspension control system in a manner known for example from DE 10 2005 060 173 AI a control device 14, which receives in the present embodiment arranged on each wheel 8 angle sensors 16 rotation angle 18, which is a relative position of the corresponding wheel 8 against describe the chassis 6. The angles of rotation 18 are transmitted in non-referenced output signals between the angle sensors 16 and the control device 14. Based on the differences of these angles of rotation 18, the control device 14 determines whether the chassis 6 moves in the vertical axis 10, that is, performs a lifting movement, or whether the chassis 6 wobbles or nods and controls. In this case, the control device 14 calculates one of these lifting, rolling and / or pitching counteracting counter-movement and controls with appropriate control signals 20 arranged on the wheels 8 active struts 22 to compensate with the chassis 6, this counter-movement. As active struts 22, for example, known from DE 101 22 542 B4 struts can be used.

In order to take account of lifting, rolling and / or pitching movements caused by the road situation, for example during cornering, a suitable nominal value 24 can be supplied to the control device.

Referring to FIG. 2, an example of an angle sensor 16 of FIG. 1 is shown.

In the present embodiment, the angle sensor 16 has a circuit housing 26 that can be connected in a stationary manner to the chassis 6 in the vertical axis 10. For this purpose, not further visible mounting holes 27 are formed on the circuit housing 26 through which a not further shown fastening means, such as a screw can be performed. In the circuit housing 26 is an evaluation circuit 28, housed in the form of a to be described from a donor element in the form of a Magnet 30 receives a physical field in the form of a magnetic field 32. The magnet 30 is rejected by the evaluation circuit 28 with an air gap 31, which is dependent on the rotation angle 18 in the present embodiment. This will be discussed later. Through a through opening 34 of the circuit housing 26 a rotatable about an axis of rotation 37 encoder shaft 38 is received, on which the magnet 30 is held at an axial end 39. From the opposite end of the magnet 30 axial end 40 of the encoder housing 38 protrudes at right angles from a lever 41, at whose radial end a mounting hole 42 is formed, on which the angle sensor 16 in the vertical axis 10 fixed to one of the wheels 6 is connectable. Moves the corresponding wheel 6 in the vertical axis 10 relative to the chassis 6, so the wheel 6 also moves the lever 41 and thus rotates the encoder shaft 38 relative to the circuit housing 26 with the rotational angle to be transmitted 16. Thus, magnetic field 32 moves relative to the evaluation circuit 28 with the angle of rotation 18. The moving magnetic field 32 thus changes in dependence of the rotation angle 18 relative to the evaluation circuit 28 in its magnetic field strength, which detects the evaluation circuit 28 metrologically, for example via a known per se Hall element in the evaluation circuit 28 and at an output interface 46 in an angle of rotation 18 carrying not further shown output signal in the manner shown in Fig. 1 to the control device 14 can be transmitted. The angle sensor 16 will be explained below with reference to FIG. 3 in more detail.

As seen in FIG. 3, the magnet 30 in the present embodiment is elliptical. In this case, the magnet 30 is constructed elliptical in the axis of rotation 37 of the encoder shaft 38 seen both in an axial cross section and in a radial cross section. In principle, however, it would also be possible to magnet 30 but only in a radial or axial cross-section form elliptical.

The field poles, which include a north pole 50 and a south pole 52 in the magnet 30, are separated in the present embodiment by the minor axes of the elliptical cross sections, so that the field poles 50, 52 in the present embodiment in the main vertex points 54 of the elliptically shaped magnet 30th lie. Alternatively, however, the field poles could also be separated by the major axes of the elliptical cross sections.

By elliptical design of the magnet 30 in the axial

Cross-section of the magnet 30, two axial projections 56 are formed on the magnet 30, which in the radial direction of the

The axis of rotation 37 of the encoder shaft 38 from the magnet 30 jump out. Accordingly, two projections 58 are formed by the elliptical formation of the magnet 30 in a radial cross section, which project in the axial direction of the axis of rotation 37 from the magnet 30 from. Due to the elliptical design of the magnet 30, the field poles 50, 52 are formed point-symmetrical to a point of symmetry 59 on the axis of rotation 37.

By the projections 56, 58 of the air gap 31 is formed variable in dependence of the rotation angle 18. This means that the shortest distance between the magnet 30 and the evaluation circuit 28 varies as a function of the angle of rotation 18. The variable air gap 31 causes the magnetic field strength of the magnetic field 32 of the magnet 30 to be changed not only by the movement of the magnet 30 itself but also by this varying air gap 31 as a function of the angle of rotation 18. Thus, the rotation angle 18 in the output signal output from the evaluation circuit 28 can be generated not only based on the movement of the magnet 30 itself but also based on the variation of the air gap 31. In particular, the protruding projection 58 in the axial direction should fit in the circumferential direction of the rotation axis 37 and thus in the direction of the rotation angle 18 as accurately as possible in a detection range 60 of the evaluation circuit 28, in which the Magnetic field 32 of the magnet 30 is detected. In this way it is ensured that the variable air gap 31 changes in each position based on a change in the rotation angle 18 and leads to a change in the output signal from the evaluation circuit 28.

The magnet 30 may be molded onto the axial end 39 of the encoder shaft 38. 4, in which the encoder shaft 38 is shown in a state before the magnet 30 is molded onto the encoder shaft 38.

At the axial end 39 of the encoder shaft 38, an elliptical and ausgeholtes retaining element 62 is formed in the present embodiment in which two walls 64 are added, which are to serve as rotation for the magnet 30.

In this hollowed-out holding element 62, a magnetic material is injected. As a magnetic material, for example, as a filler, a plastic such as polyamide,

Polyphenylene sulfide or the like can be used. A magnet powder, for example based on hard ferrite or NdFeB-based, may be embedded in this plastic. The magnetization of the injected material can be done directly during the injection or after the injection process is completed.

Alternatively, at the axial end 39 of the encoder shaft 38, a magnet prepared beforehand, for example, by sintering may be fastened, for example by gluing.

In Fig. 5, an example of a molded magnet 30 is shown, in which the magnet 30 has an axially directed projection 58.

Claims

claims

1. sensor (16) for outputting a rotation angle of an (18) dependent output signal comprising

a shaft (34) rotatable about the angle of rotation (18),

a field donor member (30) mounted for rotation against an axial end (39) of the shaft (34) for delivering a physical field of view (32) and

one with an air gap (31) spaced from the field generator element (30) arranged evaluation circuit (28) for generating the output signal based on the physical

Measuring field (32),

wherein the field sensor element (30) is formed such that the air gap (31) is variable in dependence on the angle of rotation (18).

2. Sensor (16) according to claim 1, wherein the variable

Air gap (31) is defined as a function of the rotation angle (18) as the shortest distance between the field sensor element (30) and the evaluation circuit (28).

3. Sensor (16) according to claim 1 or 2, wherein the field sensor element (30) in the circumferential direction to the rotation angle (18) considered two field poles (50, 52) and the variable air gap (31) is least, if one of the two field poles (50, 52) parallel to a line through a rotation axis (37) of the shaft (38) and the evaluation circuit 28 is located.

4. Sensor (16) according to any one of the preceding claims, wherein the variable air gap (31) by at least one radially and / or axially from the field generator element (30) projecting projection (56, 58) is formed.

5. Sensor (16) according to any one of the preceding claims, wherein the variable air gap (31) by at least two radially and / or axially projecting from the field sensor element projections (56, 58) is formed, the point symmetrical to each other (59) are arranged.

6. Sensor (16) according to any one of claims 4 or 5, wherein the projection (56, 58) is substantially equal to a detection range (60) of the evaluation circuit (28) in the direction of the rotation angle (18).

7. Sensor (16) according to any one of the preceding claims, wherein the field transmitter element (30) of the shaft (38) from the evaluation circuit (28) viewed in the axial and / or radial direction is elliptical.

8. Sensor (16) according to any one of the preceding claims, wherein the field sensor element (30) is a magnet (30).

9. sensor (16) according to any one of the preceding claims, wherein the field sensor element (30) axially spaced from the shaft (38) and radially spaced from a rotational axis (37) of the shaft (38) is arranged.

10. A method for producing a for outputting a dependent of a rotation angle (18) dependent output signal sensor (16), in particular according to one of the preceding claims comprising

Providing a shaft (38) rotatable about the angle of rotation (18),

Injecting a to output a physical

Measuring field (32) field sensor element (30) at an axial end (39) of the shaft (38), so that with the Feldgeber- element (32) based on the rotation angle (18), the physical measuring field (32) can be dispensed, and

Arranging an evaluation circuit (28), viewed axially from the shaft (38), in front of the field generator element (30), which is arranged to generate the output signal based on the physical measuring field (32).